Compressor type heat exchange systems generally comprise a compressor in combination with a refrigerant either to absorb heat from or to release heat into ambient atmosphere. In either case, this is accomplished by cycling a gaseous refrigerant through the heat exchange system under pressure. More particularly, a compressor of the heat exchange system compresses the gaseous refrigerant cycled therethrough into a liquid so that the expansion and contraction properties of the refrigerant may be utilized to alter the temperature of the refrigerant and effect heat absorption.
There are generally two types of compressor heat exchange systems. There is an air-conditioning or refrigeration system which is designed to take heat from a building or an enclosure, respectively, and transfer it to ambient environment. There is also a heat pump system which is designed so that it can take heat from the ambient environment and transfer it into the interior of a building, or it can reverse the action and function as an air-conditioning or refrigeration system.
As already recited above, both of these heat exchange systems rely upon a refrigerant in a pressurized state to alter temperature. The most common of these refrigerants are halogenated hydrocarbons, particularly chlorofluourocarbons (CFCs) such as dichlorodifluoromethane and the like. The CFCs are generally referred to as freons, and they normally exist in a gaseous state under ambient conditions. When CFCs are introduced into heat exchange systems, however, the compressors utilize work to place the refrigerants in a pressurized state and convert them into liquid form.
Because air-conditioning and refrigeration systems are usually operated heavily during the warmer months of the year, it is not uncommon for the refrigerants, which are being continuously cycled therethrough, to become contaminated with particulate or liquid matter. Unfortunately, in those situations where the refrigerants are permitted to become too contaminated, their ability to transfer heat is dramatically reduced due to the degradation of their thermal dynamic properties. To avoid such a problem, it has been the standard practice in the industry to periodically replace the refrigerants.
In addition to replacing contaminated refrigerants, air-conditioning and refrigeration systems on occasion become disabled requiring repair. During such repair, it is likewise necessary to remove the refrigerants from such systems. If the compressors are functioning, the people servicing such systems are fortunate in that they can utilize the compressors to force the refrigerants into collecting cylinders. If, however, the compressors are disabled, the service people must resort to other means to transfer the refrigerants into the collecting cylinders. This is particularly troublesome for the service people by reason of the fact that they are unable to determine if the compressors are functioning until actual inspection thereof and that such systems are normally located in remote, difficult-to-reach places, such as on rooftops.
Today, there are available separate mechanical units adapted to collect and decontaminate refrigerants from heat exchange systems. Exemplary of such mechanical units are disclosed in U.S. Pat. Nos. 4,539,817 and 3,232,070. Although these mechanical units are ideally suited to service air-conditioning units in automobiles, and units located at ground level, they do not provide a realistic solution to the above problem. First of all, such mechanical units are relatively bulky, heavy pieces of equipment often weighing in excess of 100 lbs. Secondly, since most heat exchange systems, such as air-conditioning units for office and industrial establishments and the like, are located in inaccessible areas, such as on rooftops where ladders are the only mode of access, it is virtually impossible to service such heat exchange systems with these mechanical units. Simply put, these mechanical units are too large and too heavy to pick-up and carry. This is evidenced by the fact that these mechanical units are typically mounted on wheels to counter their weight and bulkiness, and to improve their portability.
In the past, when replacing contaminated refrigerants or servicing disabled heat exchange systems, the practice was simply to tap open such systems, vent the refrigerants into the environment, service the systems if necessary, and introduce fresh, decontaminated refrigerants into the systems. Up to now, this has been a widely accepted practice in the industry for two reasons. First, there has been no governmental restrictions prohibiting the release of such refrigerants into the environment. And second, the cost of new refrigerants is negligible.
However, this practice is rapidly changing because of the negative environmental impact which the CFCs have had on the ozone layer. According to the Environmental Protection Agency (EPA), refrigerants such as the CFCs can no longer be vented to atmosphere and must be collected and properly disposed of or reused. In addition, since the cost of the refrigerants is continuing to rise, it is becoming economically prudent to rejuvenate and reuse refrigerants rather than to vent them into the environment. This is particularly true in view of the fact that decontaminated refrigerants can be reused and that there is a simple and economical process available today for decontaminating refrigerants such as CFCs once they have been collected.
Other than the use of undisabled compressors or mechanical units to compress the refrigerants removed from the heat exchange units into collecting cylinders, the alternate method available today is to simply reduce the pressure within a collecting cylinder by chilling the cylinder so that the refrigerants can be collected therein in liquid form. As the refrigerants enter the chilled collecting cylinders, the reduced pressure and cooler environments within the interiors thereof keep the refrigerants in a condensed or liquid condition and flowing from the heat exchange systems into the chilled cylinder i.e., the refrigerants flow from hot to cold. Normally, refillable 20-50 lb. or larger collecting cylinders are employed, and when used for this purpose, they are typically filled with refrigerants to about 80% of their capacity.
The above described procedure has been accomplished heretofore by exposing the outer surface of the collecting cylinders to dry ice. Unfortunately, the use of dry ice is not without its drawbacks. For instance, dry ice is very heavy, it is dangerous and difficult to handle due to its extremely low temperatures, and it is not readily available due to the fact that it cannot be stored over long periods of time under these types of working conditions. Moreover, since service people, when servicing disabled heat exchange systems, are unable to determine if the compressors are functioning until they actually inspect same, the service people do not know if dry ice should initially be brought with them to the sites. Accordingly, even though dry ice has had limited practicality in chilling exterior surfaces of collecting cylinders for reclaiming refrigerants from heat exchange systems, dry ice is generally unsuited for use in this application.
Consequently, there is an immediate commercial need to improve the process of collecting contaminated refrigerants or refrigerants from disabled heat exchange systems located in remote, difficult-to-reach locations, such as on rooftops, without having to resort to the use of dry ice or bulky, heavy mechanical units.